1. Technical Field
The present invention relates to a gate driver, and more particularly, to a gate driver capable of reducing the number of gate-driving integrated circuits.
2. Related Art
Liquid crystal display (LCD) devices may display an image by using an electric field to control the light transmittance of liquid crystal having a dielectric anisotropy. Some LCD devices include an LCD panel having a pixel matrix, and a driving circuit for driving the LCD panel.
FIG. 1 is a block diagram of a related art LCD device. In FIG. 1, the related art LCD device includes a liquid crystal panel 2. The liquid crystal panel 2 includes a pixel matrix. The LCD device may also include a gate driver 4 for driving gate lines GL1 to GLn of the liquid crystal panel 2, a data driver 6 for driving data lines DL1 to DLm of the liquid crystal panel 2, and a timing controller 8 for controlling driving timings of the gate driver 4 and data driver 6.
The pixel matrix of the liquid crystal panel 2 includes pixels formed in regions defined by intersections of the gate lines and data lines. Each pixel includes a liquid crystal cell Clc for controlling an amount of light passing through the pixel, and a thin film transistor (TFT) for driving the liquid crystal cell Clc.
Each TFT is turned on in response to a scan signal, such as a gate high voltage, VGH, supplied from an associated gate line GL. In an ON state, the TFT may supply a pixel signal, received from the associated data line DL, to an associated liquid crystal cell Clc. Each TFT is turned off in response to a gate low voltage VGL supplied from the associated gate line GL. In the OFF state of the TFT, the pixel signal charged in the associated liquid crystal cell Clc is sustained.
Each liquid crystal cell Clc can be equivalently represented as a capacitor. Each liquid crystal cell Clc includes a common electrode and a pixel electrode facing each other at opposite sides of the liquid crystal cell Clc. The pixel electrode is connected to the associated TFT. Each liquid crystal cell Clc may further include a storage capacitor (not shown) which may sustain the charged pixel signal until the next pixel signal is charged. In accordance with this structure, the orientation of the liquid crystal in each liquid crystal cell Clc is varied in accordance with the pixel signal charged via the associated TFT because the liquid crystal has a dielectric anisotropy, thereby causing the light transmittance of the liquid crystal to be adjusted. Thus, a desired gray scale is obtained.
The gate driver 4 shifts a gate start pulse, GSP, supplied from the timing controller 8 in response to gate shift clocks, GSC. The gate driver 4 can sequentially supply the shifted pulses as scan pulses having a gate high voltage, VGH, to the gate lines GL1 to GLm, respectively. In a period when no scan pulse has a gate high voltage, VGH, the gate driver 4 supplies a gate low voltage, VGL. The gate driver 4 includes a plurality of gate-driving integrated circuits (ICs) to drive the gate lines GL1 to GLn in a grouped manner.
The gate-driving ICs may be mounted on tape carrier packages, TCPs, in a grouped state so that they are connected to the liquid crystal panel 2. The TCPs carrying the gate-driving ICs are attached to the liquid crystal panel 2 through a tape automated bonding, TAB, process.
In the related art LCD device using a plurality of gate-driving ICs to drive the gate lines GL1 to GLn, an increase in manufacturing costs occurs when the number of the gate lines is increased to obtain a desired resolution. The increase in the number of gate lines causes an increase in the number of gate-driving ICs and the number of TCPs. Therefore, there is a need for an improved gate driver.